Light-Emitting Diode (LED) is a two-terminal electronic component that emits light when a sufficient voltage is applied across its terminals. The emitted light color is determined by the materials and manufacturing process used, as well as other electronic characteristics. Each LED is designed to emit a specific color based on its material and manufacturing. In cases where a product requires a particular color or color change, Red, Green, and Blue (RGB) LEDs are used in combination to create the desired color using the RGB color model. Please note that this paragraph does not cover the RGB color model; instead, it focuses on choosing the most cost-effective colored LED for your product.

Why do product designers need the lowest-cost colored LED?

Theoretically, any LED color can be achieved by adjusting the materials and manufacturing process. However, producing every possible LED color would result in extremely high production costs for LED factories. To reduce costs and ensure profitability, LED factories focus on mass-producing the most commonly used colored LEDs.

You can think of an LED as a light bulb. When a light bulb is powered correctly, it emits light with a specific color and brightness that was determined during the manufacturing process. To minimize costs, factories choose a range of LEDs with the most commonly used colors and brightness levels. RGB light bulbs are used for applications requiring specific colors instead of creating a unique color for each instance. By selecting from existing LED color series for your product, you can reduce the overall cost.

How to express color in LED?

Expressing a specific color can be challenging. For example, consider the blue color shown in the picture below.

Different individuals may perceive this blue differently, such as sky blue, water blue, or even Ferrari blue. Additionally, factors like variations in monitors and printing can affect how colors appear.

　　To address this, some companies have developed color card systems, such as the Pantone color system, to ensure consistent color representation throughout the design process.

　　In the case of Light-Emitting Diodes (LEDs), we use the wavelength of emitted light to express the color. Following the visible light spectrum, we classify visible light into seven colors: red, orange, yellow, green, cyan, blue, and violet.

Most commonly used LED emitting colors for LED makers:

The most frequently used LED emitting colors are blue, amber, orange-red, red, yellow, yellow-green, and pure green. The following table shows the color names and corresponding colors.

Sometimes, the color “orange-red” may also be referred to as “red-orange.” Both expressions denote the same color, which lies between orange and red. However, it is uncommon to refer to yellow-green as green-yellow. Additionally, white is another commonly used LED emitting color. However, discussing the details of white color goes beyond the scope of this article.

If you require a color not listed in the table above, it would require a custom LED, which comes at a higher price. Therefore, it is important to choose the right color for low-budget product designs.

Wavelength range for the 7 most commonly used LED emitting colors:

Each LED display uses different LEDs, and the datasheet only provides the LED emitting color specification.

Different wavelength ranges for each LED emitting color

For every LED maker, the wavelength range for the same color may vary. For example, the amber color in OPS-S5620(1)SA and OPD-M25710(1)LA has different wavelength ranges. It is important to check the specific wavelength range when the application requires an exact colored LED.

Conclusion

　　This article provides a brief introduction to the seven most commonly used LED emitting colors. It discusses how LED defines color and how each LED factory defines their colors. Product designers have the option to choose the lowest-cost LED color from the early stages of the design process.